The present invention relates to magnetic devices. More particularly, the present invention relates to a magnetic device that employs a current-carrying conductor to provide a magnetic field that assists a write field.
As magnetic recording storage densities continue to progress in an effort to increase the storage capacity of magnetic storage devices, magnetic transition (i.e., bit) dimensions and critical features of the recording device are being pushed below 100 nm. In addition, making the recording medium stable at higher areal densities requires magnetically harder (i.e., high coercivity) storage medium materials. A magnetically harder medium may be written to by increasing the saturation magnetization value of the magnetic material of the recording device to increase the magnetic field applied to the magnetic medium. However, the rate of increase of the saturation magnetization value is not sufficient to sustain the annual growth rate of bit areal densities.
Another approach to overcoming the coercivity of a magnetically hard medium is to provide a stronger write field by incorporating a write assist device adjacent to the tip of the write pole that produces a magnetic field to reduce the coercivity of the magnetic medium near the write pole. This allows data to be written to the high coercivity medium with a lower magnetic field from the write pole. In addition, the field gradient around the write pole tip is improved due to cancellation of stray fields from the write pole in regions that the assisting field opposes the write field. However, the regions in which the assist field opposes the write field are generally a distance from the write pole tip, and thus the gradient improvement is limited in the region in which transitions are written to the magnetic medium.